Earth moving, construction and mining equipment and the like are often used in rough, off-road terrain. These machines often employ an endless drive with track shoes that is better able to propel the machines in such environments over obstacles and uneven terrain, etc. The track chain assemblies, which include shoes, are held together by a series of interconnected track links, pins and bushings that are supported on the drive sprocket, idler and support rollers of the machine. The drive sprocket, is so called, as it may drive or convey power to the track chain assembly, causing it to revolve about the idler wheels, resulting in linear motion of the machine.
The drive sprocket includes lugs that fit between various inside and outside links of the track chain assembly and typically contact a track chain bushing that spans between the adjacent inside track links and outside track links. As the drive sprocket rotates, a first lug pushes the track chain assembly along a direction by pushing on the track chain bushing. Eventually, the first lug disengages the track chain bushing as a second lug disposed immediately behind the first lug contacts another track chain bushing, forcing the track chain assembly to continue to move along the same direction.
As can be imagined, there can be a great deal of force on the lugs and abrasive material such as sand, dirt, rocks, etc. may cause the lugs to wear over time. The lugs may become worn to the point that the lugs can no longer effectively contact the track bushings or otherwise propel the movement of the track chain assembly. When this happens, the machine and track will need to be serviced. Repairing or replacing sprockets and/or their lugs may be time consuming or be costly in other ways.
One proposed solution to these problems has been disclosed in U.S. Pat. Application Publication No. 2014/0333125 to Hoyt. FIGS. 3, 6 and 14 of Hoyt show a plurality of teeth 150 extending radially outwardly from a sprocket hub 152. The sprocket hub may further include a plurality of radially extending mounting projections 162. Each tooth may be secured to each projection by a set screw or a retention pin 222. It has been found that these retention methods have not been as robust as desired. Retention pins and set screws may become loose and fall out. If this happens, then the tooth may become loose and fall off the drive sprocket. If this occurs in the field, the machine may have to be towed back to a servicing station or serviced in the field. Either scenario may be inconvenient or costly.